F21 systemd log flood - how to stop

I'm having trouble with systemd flooding /var/log/messages with every cron job. I've tried setting LogLevel=emerg in /etc/systemd/system.conf (and ran systemctl daemon-reload, and systemctl daemon-reexec, and rebooted), as well as trying systemd-analyze set-log-level emerg. No effect.

The first time I tried system.conf, I mistakenly put LogLevel=warn. At every boot, I get the error message
systemd[1]: [/etc/systemd/system.conf:11] Invalid log level'warn': Operation not permitted
But I've changed it from warn to emerg, did daemon-reload, and daemon-reexec, and multiple reboots, and it's still giving me this error.